class Solution {
public:
    vector<int> printMatrix(vector<vector<int> > matrix) {
        vector<int> res;
        
        if(matrix.empty()){
            return res;
        }
        
        int n = matrix.size(), m = matrix[0].size();
        vector<vector<bool>> state(n, vector<bool>(m, false));
        int dx[4] = {-1, 0, 1, 0}, dy[4] = {0, 1, 0, -1};
        int x = 0, y = 0, d = 1;
        
        for(int i = 0; i < n * m; i++){
            res.push_back(matrix[x][y]);
            state[x][y]=true;
            
            int a = x + dx[d], b = y+ dy[d];
            if(a<0||a>=n || b<0 ||b>=m ||state[a][b] == true){
                d = (d+1)%4;
                a=x+dx[d], b = y+dy[d];
            }
            x=a, y=b;
        }
        
        return res;
    }
};